Phosphorylation is a post-translational modification that is known to regulate many aspects of cellular function, including the mechanisms which underlie synaptic plasticity. PICK1 is a neuronal protein known to be involved in AMPA receptor trafficking, and which has been shown to interact with PKCa and act as a substrate for this conventional PKC isoform. This study further investigates the phosphorylation of PICK1. Phosphorylated regions of PICK1 are first identified through the use of a radioactive phosphorylation assay and serine-412 in the C- terminus of PICK1 is identified as a phosphorylated residue. The kinases involved in PICK1 phosphorylation are then investigated and it is shown that the atypical PKC isoform PKMζ is likely to be the kinase responsible for phosphorylating PICK1 at serine-412. Corroboration of this comes from the finding that PICK1 interacts with PKMζ, and that treatment with the PKMζ inhibitory peptide ZIP reduces the signal obtained from a phosphospecific antibody targeted against PICK1 phosphorylated at serine-412. Finally, functions and signals associated with PICK1 phosphorylation are investigated. It is shown that PICK1 strengthens the known interaction of PICK1 with the actin polymerising Arp2/3 complex, and that NMDA treatment decreases the observed level of PICK1 phosphorylation.